Concept, Types, Principle of inertia and Examples

We explain what inertia is and what types exist.Newton's principle of inertia and everyday examples where inertia is experienced.

The seat belt overcomes the inertia of the passengers when braking or crashing.

What is inertia?

Physically inertia is called the resistance that bodies oppose to modify their state of motion or stillness , either to alter their speed, course or to stop; although the term also applies to the modifications of its physical state.

A body, like this, requires a force that overcomes inertia to alter its trajectory , which otherwise would adhere to the laws of the uniform rectilinear movement, or to initiate a movement, otherwise it would remain at rest.This, of course, considering that there is no rest or rectilinear and uniform movement in the universe, except based on a system of reference (of observation).That is why it is preferred to speak of “relative rest.”

In this way, a body or system will have a greater inertia insofar as it requires forces of greater intensity to modify their state of motion or to modify their physical state.These resistances are called “inertial forces” to change their state of movement or physical state, and they are fictitious forces that the observer perceives within the frame of reference.

It can serve you: Acceleration.

Types of inertia

Thus, two types of inertia are distinguished in physics: mechanics and therma.

• Mechanical inertia.Related to the difficulty of modifying movement and stillness, as we have explained above.It depends directly on the amount of mass of the body or system and the inertia tensor.


• Thermal inertia.Measures the difficulty of a body or system to modify its temperature when it comes into contact with other objects or when heated directly.It depends on the heat capacity of the body or system.

However, mechanical inertia can be further subdivided into:

• Dynamic inertia, presented by bodies in relative motion.


• Static inertia, presented by bodies at relative rest.


• Rotational inertia, presented by bodies that exhibit rotational motion.


• Translational inertia.It is linked to the total mass of the bodies.

Principle of inertia

The principle of inertia was formulated by Sir Isaac Newton.

The principle of inertia, known as the Newton's First Law , prays that bodies tend to maintain their state of rest or of uniform rectilinear movement until an external force is applied on them capable of overcoming said resistance, which is referred to as previously said, inertial force.

This principle of physics was formulated mathematically by Sir Isaac Newton in his work Philosophiae naturalis principia mathematica published in 1687, from the well-known Law of inertia of Galileo Galilei.And one of its fundamental concepts is the equivalence between the state of rest (speed 0) and that of rectilinear and uniform movement, since in both cases, if presented, they imply that no external force is acting on the body in question.

Instead, if we observe a body moving and losing speed gradually, we can attribute that loss of speed to the effect of friction forces that overcome its inertial principle.

Examples of inertia

The inertia can be verified and experienced through numerous examples.Some can be:

• The seat belt .When a vehicle travels at a constant speed, its passengers share with this speed.But if the driver suddenly stops the vehicle (or collides with another which prevents him from continuing his trajectory), the passengers will feel the thrust of the inertia that makes them keep their movement, throwing them forward.Then the safety belt intervenes, which overcomes the inertia and interrupts their movement, preventing them from hitting with the windshield./li>
  
• Pushing a heavy object .By pushing a heavy object at rest, you feel the need to overcome inertia with the force of those who push.Once defeated, the object will move more easily, as it will be in motion; but initially it will resist moving.


• Quickly throw a tablecloth .In the typical act of magicians, a tablecloth is pulled with objects on top, which remain in place due to inertial forces and do not move along with the fabric.


• Train braking .When trains seek to stop at the station, they take a while to do so, because the inertia they bring is so high that they require more braking space.


• The adobe of the constructions .The adobe is a usual construction material, especially in the most precarious houses, because it has a great thermal inertia: it resists heating, keeping the interior cooler housing.